By Alex Kutschera on December 21, 2017
This is the second part of the complete test tube photometer building instructions: The building and wiring instructions.
But if you want you can go back to the the shopping list. Here you find instructions for building the test tube photometer. If something is not completely clear to you, let us know and we will help you!
Connect sensor pin 1 to 5V, pin 3 and 8 to ground. Sensor pin is connected to pin 5 with a 1 MΩ resistor in between (see circuit diagram on the right). You can now connect the sensor output (pin 5) to any analog input pin of your microcontroller and you are ready to measure light.
Speaking of light, you still have to connect the LED with one of the digital output pins of the microcontroller to switch the light on and off.
Well, that’s basically all you need to do to use your test tube photometer. If you like you can connect an LCD display to the microcontroller to display the measured values directly. I connected my photometer to a Raspberry Pi and let them communicate via the serial connection. The microcontroller runs this script and sends the data to the Pi which calculates the OD with this python script and writes everything to a .csv file.